I happened to like the campaign, and I didn't enjoy the campaign modes on the previous 2. Plus, online really adds a lot of fun to the game. My friend and I often edit levels with Forge and produce some pretty crazy results.
The campaign is pretty boring, yes, but multiplayer is where it shines. Also, if you put the difficulty higher, you have to use a lot more strategy and hiding (which can enhance or ruin the experience, depending on how you view it).
Anyways, you've been playing ICC Cricket a lot recently so maybe you'll get used to Halo if you play it some more. I didn't like Halo 1 or 2 the first time I played them (and I never ended up liking them), but I played Halo 3 more and more and I really enjoyed it.
My only complaint is that the people online suck. Every person picks Spartan and Hayabasu (spelling?) armor, and sometimes even the sword just so they can be a big gay ninja. Plus, everyone tries to snipe whether they're good at or not. Also, 40% of people are frat dudes, 40% are little boys, 1% are actual girls, and 19% are people who don't speak English or never talk (so hell if I'd know). Pretty much everyone online is a complete idiot. But if you're used to that, then it's actually a lot of fun.
